Method of and apparatus for controlling fluid fuel burners for boilers



Patented Mar. 7, 1939` PATENT or-FICEA HETHOD 0F AND APPARATUS FOR CON-TROILING FLUID FUEL BURNERS FOR BOILERS Guido Wnsch and Kurt Blasig,Berlin-Steglitz, Germany, asslgnors to Askania-Werke A. G., a

company of Germany Application January 30, 1935, Serial No. 4,204 InGermany January 30,v 1933 13 Claims.

This invention relates to a novel method and apparatus for controllingfluid fuel burners such as oil burners used in marineboilerinstallations and the like, although it is to be understood thatthe invention is applicable to other types of installations. Among otherobjects, the invention aims to provide novel -means for controlling aseries of burners in accordance with the boiler load and alsocontrolling the individual burners of the series. The idea is to obtainsatisfactory graduated control of the burners and to avoid the necessityof employing a larger number of burners to accomplish the same result.Furthermore, the invention aims to provide a novel method whereby theindividual burners of the series start in succession and the supply offuel and air to the individual burners is increased according to theboiler load. The invention also contemplates the provision of novelmeans for controlling both the primary air and secondary air for burnersof the atomizer type in accordance with the quantity vof oil or otheriluid fuel admitted to the burners.

Other aims and advantages of the invention will appear in thespecification, when`considered in connection with the accompanyingdrawings,

wherein: 1

Figs. 1 and 1A disclose more or less diagrammatically an illustrativeexample of apparatus used for practicing the invention.

Referring particularly to the drawings, it will be assumed for thepurposes of illustration that the boiler is oi the marine type in whicha pluralityof atomizing burners' I0, Il', etc. are employed. The burnersare shown for convenience as being arranged on opposite sides ofthe-boiler furnace. In this example, fuel oil is supplied to the burnersthrough oil conduits II connected to an oil header'I2 representing asource of oil and having a series of oil control valves I3, I3' of theneedle type. In this instance, three such oil lines are shown, merely toindicate that any number of burners may be employed and controlledautomatically in accordance withthe invention.

The oil is atomized in the burners I0 and Ill by means of the ordinarycentrifugal turbines (not shown), or by any other well knownmeansemployed in the art. Primary air to support combustion is supplied bymeans of ordinary blowers I4, I4 through conduits I5 and I5 respectivelywhich terminate in nozzles around the ends of the oil conduits. Thesupply of primary air is variedby means of conduits I6, IIi7 which openinto the atmosphere and are controlled 'by butterily valves I1 and I1',said valves being I .preferably controlled automatically by apparatuslater to be described. When the butterflies are closed, the maximumamount of primary air- Will be admitted to the burners; while the airwill be vented to the outside when the butterflies are in their openposition. The butterflies are here shown as being controlledhydraulically and automatically, although it is to be understood thatAthey may be automatically controlled by any otherv suitable means.Herein, thel valves are connected to pistons I8, I8' by means of armsand links I9, I9', 20, 20 respectively' The pistons are arranged incylindershZI, 2|' and are shown as being normally urged toward the valveopening positions by means of springs 22, 22'. The hydraulic mechanismfor operating these' pistons will be described later.

In the present instance, secondary air'l is also supplied automaticallyto the burners by means of a separate blower 23 having a main outlet 24leading to the branch conduits 25, 25' and, thence, to the respectiveburners. The supply of air to the branch conduits is shown as beingcontrolled by a main damper 26 actuated by a piston 21 in a cylinder 28.The supply of secondary air to the individual burners is alsoautomatically controlled in a manner later to be described Aby dampers29, 29 in the branch conduits these dampers being actuated by pistons30, 30 in cylinders 3|, 3i'. While the volume of air delivered by theblower 23 to the branch i conduits may be controlled by 'varying thespeed of the blower, it is here shown as being controlled by thebutterfly 26 to set up a predetermined pressure difference between themain secondary air conduit and the combustion chamber of the boiler inresponse tothe total boiler load. The l manner in which the damper 26 inthe outletconduit 24 is automatically governed in response to the loadon the boiler, will be later explained. Referring to Fig. 1A, it wlllbeunderstood that oil under constant pressure is delivered to the headerI2. The needle valves i3, I3' and I3" are -normally held closed by meansof compression springs 34, 34', 34 and they are adapted to be operatedin succession or in series by bell-shaped cams 35, 35 and 35, thearrangement being such that the valve I3 opens first. These cams areshown as being carried on a single piston rod 36 operated by a piston 3larranged in the cylinder 38. The valves are controlled automatically inaccordance with the boiler load by means of a jet pipe regulator orgovernor of'the Askama type, reference being made to Reissue Patent No.19,114 and Patent No. 1,721,800. In this case, the steam pressure in thesteam header governs the action of the regulator by a steam conduit I9,the pressure being a measure of the boiler load. The pressure acts on abellows type diaphragm 46 which.. in turn, exercises a controllingei'fect through a spring-urged pivoted arm 4i acting upon a rod or bar42 on the jet pipe 43, which is supplied with oil or liquid underconstant pressure from a suitable source, not shown, delivered by aconduit 44. The jet pipe delivers oil to one or the other of conduitsand 46 leading to opposite ends of the cylinder 56, the arrangementbeing such that as the steam pressure increases in the header the jetdelivers oil to pipe 45 and moves the piston to the left, therebycutting down the oil supply to the burners.

In this instance, the regulator has a governing slider 41 above the jetpipe 43 acting on a counterbalanced arm 46 and normally urging a pushrod 49 against a compression spring 5U, which acts on a push rod 5icarrying a roller 52 contacting with a cam 53 on the piston rod 36. Thearrangement is such that when the piston is moved in either direction,the mechanism counterbalances the jet pipe and brings it to rest afterthe piston 31 has moved the cam 53 into a position representing thepressure in the steam header. It will be understood that when theburners are first started, there will be no pres sure in the steamheader; consequently the jet pipe will deliver-oil to the conduit 46 andmove the piston 31 tothe right to open the oil valves in succession.When the pressure rises to a predetermined amount, further movement ofthe piston -is arrested by the governing apparatus through the cam 53.

As hereinbefore stated, the primary and secondary air are alsocontrolled automatically. In this instance, the control is effected byhydraulic relay mechanism; although it is to be understood that it maybe operated electrically or otherwise. Herein, oil under constantpressure is delivered to a header 54 having a series of main outletvalves 55, 55 and 55 opposite the fuel oil valves and leading to casings56, 56', 56 and these valves are normally held closed by compressionsprings 51, 51 and 51" on their stems which are actuated by the cams 55,l5. 35". The valve stems carry second valves 58, 58', 58 controllingreturn ports 5S, 59', 56" leading to a common return conduit 6l. Thearrangement is such that when one of the outlet valves- 55 is fullyopened, the corresponding return valve is closed. From the casings 56,56 conduits 6i, 6i' lead directly to the inner ends oi' cylinders 2i,2|'. As the oil pressure in these conduits increases in response to theopening of the fuel oil valves i3, I3. the pistons I6, I5 are movedoutwardly against the springs butterflies i1, i1' in proportion to thequantity of fuel oil supplied. Simultaneously, the oil pressure isadmitted to the upper ends of four-way valve casings 62, 62', 62",having controlling pistons 63, 63', 63" on the upper ends of piston rods64, 64', 64, the piston rods being normally urged upwardly by adjustablecompression springs 65, 65', 65" at their lower ends. The springs are soadjusted that a predetermined oil pressure, measured by the pressuregauges at the upper ends of the valve casings, is required to actuatethe relay valves. The arrangement is such that when a predeterminedminimum quantity of fuel oil is supplied the relays will operate 22,22', thereby closing the immediately to fully open the dampers in thesecondary air branch conduits and thereby admit a supply of secondaryair.

Referring to the ilrst four-way valve, for example, the oil pressure inline 6| has forc'd the piston 6I downwardly. The piston rod carriespairs of spaced pistons 66 and 51 in the casing which control the portsof pairs o! conduits 65. 69 and 1l and 1i, respectively connected to thecylinder 3i and'to the return line 12 leading to a tank 13 from whichoil is supplied by a constant pressure pump to the casing of the fourwayvalve through supply line 14. In this instance, the same pump suppliesoil under pressure to all of the four-way valve casings and the returnlines lead to the tank. Of course, any source of oil under constantpressure may be employed. The supply conduit 14 leads into the casingbetween the pistons 66 and 61 so that oil may be delivered either to theconduit i8 or 1l, depending upon the position of the valve. In theposition shown, oil under pressure is being supplied to the conduit 10so that it moves the plston 30 to the right and fully opens the damper29 in the secondary air conduit 25. At the same time, oil is beingexhausted or returned from the right hand end of the cylinder 3| throughthe conduit 68 and the return line 69. The second relay has fully openedthe secondary air damper 29 after the oil valve i3' is only slightlyopened. When the pistons are at the upper end of their stroke and nofuel oil is being supplied to a burner, the oil under pressure passesthrough the conduit 68 to move the piston 30 to the left and close thebutterfly valve 29 (see the position of the parts in the casing 62) Itis sometimes desirable also to control the quantity of secondary air inaccordance with the boiler load. To this end a second main regu latorcontrols the damper 26 in the dischargeoutlet 24 of the secondary bloweror fan 22 to create a differential pressure between the boiler furnaceand said main secondary air conduit in response to the load representedby the position of a cam relatively to a push-rod 15. This regulator is'similar to the regulator for controlling the fuel oil valves. It alsoincludes a jet pipe 15 which receives oil under constant pressure from aconduit 16 and discharges into conduits 11 and 18 leading to thecylinder 26. The position of the jet pipe is controlled by a rod 19acted upon by a. cam 60 on the piston rod 36 and counterbalanced by thedifferential pressure acting on a diaphragm Il in a diaphragm casing 62which is connected by conduits Il and 64 to the main secondary airconduit and the boiler furnace, respectively. The diaphragm is shown ashaving a rod which acts on a pivoted, counterbalanced lever 66 and anadjustable slider 81 which engages the jet pipe. As the boiler loadincreases and the fuel oil valves are opened to a greater extent, theregulator acts to admit oil under pressure through the conduit 11 tooperate the piston 21 and open the damper 26. thereby increasing thevolume of secondary air. When the differential pressure between theboiler furnaces and the main secondary air conduit exceeds apredetermined amount, it will tend to move the jet pipe 15 in theopposite direction.

From the foregoing description it will be seen that the novel controlmethod enabling a control of heat supply, variable within great limits,is characterized by a step-by-step control at low load values, namely bystarting and shutting oil Cir Having thus described the method andillus-k trative apparatus for practicing the invention, it

will be understood that the invention is not limited to a strictconformity with the description thereof, but is capable of variousembodiments and modifications, within the scope of the appended claims.

What is claimed is:

l. In a boiler installation having a plurality of fluid fuel burners;separate valves for controlling the supply of fuel to the burners;a'regulator actuated by variations in the boiler load; a series of camsfor operating said valves connected to be actuated by said regulator; aseries of hydraulic relays for controlling the supply of air to saidburners; and a series of controlling valves for said hydraulic relaysalso connected to be actuated by said cams.

2. In a steam boiler installation having a' plurality of fluid fuelburners and blowers for supplying primary and secondary air thereto,separate valves for controlling the supply of fuel to the burners; aregulator connected to operate the valves in succession in response tothe boiler load; adjustable means to control the initial supplyofsecondary air when each burner is started and to control the supply ofprimary air according to the quantity of fuel supplied to the burners;and a second regulator connected to control the Volume of air deliveredby the secondary air blower in response to the boiler load.

3. The combination with a steam boiler having a plurality ofvfiuid fuelburners, of a source of fuel; a source of combustion air; meansconnected to be operated in response to the magnitude of the boiler loadbelow a predetermined low load value, for successively renderingoperative and maintaining at' a minimum capacity the fluid burners, oneafter another, means for equally and simultaneously increasing the fuelsupply to all burners when exceeding said low load value after renderingoperative the last of said burners; and means connected to be operatedin response to the boiler load for governing the combustion air supplyto all operating burners.

4. The combination with a steam boiler having a plurality of fluid fuelburners, of a source of fuel; a source of combustion air; meansconnected to be operated in response to the magnitude of the boiler loadbelow a predetermined low load value for successively admitting aminimum amount of fuel to the burners, one after the other, means forequally increasing the fuel f supply to all burners when exceeding saidlow load value after admitting fuel to the last of said burners; andmeans connected to be operated in response to the boiler load forgoverning the combustion air supply to all operatingk burners.

5. The combi-nation with a steam boiler having a plurality of fluid fuelburners, of a source of fuel; a source of combustion air; meansconnected to be operated in response to the magnitude of the boiler loadbelow a predetermined low load value for successively admitting aminimum amount of fuel to the burners, one after the other, means forequally increasing the fuel supply to all burners when exceeding saidlow load value after admitting fuel tothe last of said burners; meansconnected to be operated in response to the boiler load for governingthe combustion air supply to the burners; and means for shutting off anair supply to dead burners.

6. The combination with a steam boiler having a plurality of fluid fuelburners, of a source of fuel; a source of combustion air; meansconnected to be operated in response to the magnitude of the boiler loadbelow a predetermined low load value for successively admitting aminimum amount of fuel to the burners, one after the other, means forequally increasing the fuel supply to all burners when exceeding' saidlow load value after admitting fuel to the last ofsaid burners; meansfor admitting primary combustion air to the burners in response to theadmitted amount of fuel; and means connected to be operated in responseto the boiler load for governing the admission of secondary combustionair to all operating burners. l Y

7. The combination with a steam boiler having a plurality of fluid fuelburners, of a source of fuel; a source of combustion air; meansconnected to be operated in response to the magnitude of the boiler loadbelow a predetermined low load'value for successively admitting aminimum amount of fuel to the burners, one after the other, means forequally increasing the fuel supply to all burners when exceeding saidlow load value after admitting fuel to the last of said burners; meansfor admitting primary combustion air to the burners in response to theadmitted amount of fuel; means connected to be operatetd in response tothe boiler load for governing the admission of secondary combustion airto all burners; and means for shutting off the supply of secondary airto dead burners.

8. In combination with arsteam boiler having a plurality of fluid fuelburners, automatic control means responsive to changes in boiler loadbelow a predetermined low load value and con-1 nected to successivelyadmit a minimum amount of fuel to the burners, one after the other,means for equally increasing the supply of fuel to all burners whenexceeding said low load valve after admitting fuel to the last of saidburners; automatic governing relays also connected to be operated bysaid control means; means controlled by said governing relays forsupplying primary air to the respective burners whereby both the supplyof primary air and fuel are controlled in proportion to the boiler load;means for supplying'secondary air to the burners in response to theboiler load; and automatic means also connected to be operated by saidgoverning relays and arranged to admit secondary air to operatingburners and to shut off a supply of secondary air to dead burners.

9. In combination with a steam boiler having a plurality of fluid fuelburners, automatic control rneans'including` a master regulatorresponsive to variations in the boiler load below a pre-' determined lowload value, and a plurality of master cams, one for each burner,operable by "said'regulator and connected successively to control theadmission of a minimum amount of fuel to the burners, one after theother, means for equally and simultaneously increasing the fuel supplytoall burners when exceeding said low load value after admitting fuel tothe last of said burners; automatic governing relays also connected tobe operated by said control means;

means controlled by said governing relays for supplying primary air tothe respective burners, whereby both the supply of primary air and fuelare controlled in proportion to the-boiler load; means for supplyingsecondary air to the burners; and automatic means also connected to beoperated by said governing relays and arranged to admit secondary air tooperating burners and to shut'oi! a supply of secondaryair to deadburners.

10. Apparatus as set forth in claim 9 comprising in addition anadditional regulator responsive to changes in boiler load and connectedto control the total supply of secondary air.

11. In a steam boiler installation having a plurality o! uid fuelburners, impulse means connected to be operated in response tovariations in the boiler load; means controlled by said impulse means tostart and shut oil.' said burners one after the other in response toboiler load impulses of a predetermined low load impulse range whichcorresponds to a low operating capacity of the burners individually andcollectively; said impulse controlled means also being connected toincrease or decrease the supply of fuel to all of the burnerssimultaneously after all burners have been started at their collectivelow operating capacity and in response to impulses of a higher loadrange corresponding to the capacity range of the collective burnersexceeding their collective low operating capacity; and means connectedto supply combustion air at all times to the operating burners inresponse to the boiler load impulses.

12. In a steam boiler installation having a plurality of fluid fuelburners, impulse means connected to be operated in response tovariations in the boiler load; means controlled by said impulse means tostart and shut off said burners one after the other in response toboiler load impulses of a predetermined low load impulse range whichcorresponds to a low operating capacity of' the burners individually andcollectively; means also con- 'trolled by said impulse means connectedto increase or decrease the fuel supply to all operating burners equallyand simultaneously in response to higher load impulses corresponding tothe collective high load capacity of theburners exceeding theircollective low operating capacity; means for supplying primary air atall times to each burner in response to the amount of fuel burnt by thesame; and means for supplying secondary air at all times to theoperating burners in response to the boiler load. i

13. The combination with a steam boiler installation having a pluralityof uid fuel burners, of a source of fuel; means responsive to the boilerload connected to start the burners, one after another, and operatingeach of the burners at a. minimum capacity started; means connected toincrease the supply of fuel simultaneously to all of the burners as theboiler load further increases; and means also responsive to the boilerload to control the combustion air supply to all operating burners.

GUIDO WNSCH. KURT ausm.

until all burners have been

